Pressure-sensitive adhesive type optical film and image display

ABSTRACT

A pressure-sensitive adhesive type optical film which comprises an optical film and a pressure-sensitive adhesive layer superposed on at least one side thereof through an anchor layer formed from a resin emulsion. It is easy to handle because the pressure-sensitive adhesive does not peel off even when an edge of the film comes into contract during handling in use.

FIELD OF THE INVENTION

The present invention relates to a pressure sensitive adhesive opticalfilm having a pressure sensitive adhesive layer laminated on at leastone surface of the optical film. Specifically, it relates to an imageviewing display using the pressure sensitive adhesive optical film, suchas liquid crystal displays, organic EL displays, and PDPs. As theoptical films, polarizing plates, retardation plates, opticalcompensating films, brightness enhancement films, etc., and furthermoreoptical films with the films laminated to each other may be mentioned.

BACKGROUND ART

In liquid crystal displays etc., an image forming system necessarilyrequires polarizing elements disposed on both sides of a liquid crystalcell, and, in general, polarizing plate(s) are adhered thereto.Moreover, in liquid crystal panels, in order to improve display qualityof displays, various optical elements other than polarizing plates areincreasingly used. For example, retardation plates for prevention ofcoloring, viewing-angle expansion films for improving viewing angle ofliquid crystal displays, and furthermore, brightness enhancement filmsfor increasing contrast of displays etc. are used. These films aregenerically called optical films.

In case of adhesion of the above-mentioned optical films to liquidcrystal cells, pressure sensitive adhesives are usually used. Moreover,in adhesion between optical films and liquid crystal cells, and betweenoptical films, each material is usually attached by using pressuresensitive adhesives in order to reduce loss of light. In such a case,since it has such advantage that does not require drying stages for firmadhesion of the optical films, there are generally used pressuresensitive adhesive optical films having a pressure sensitive adhesivebeforehand prepared on one side of the optical films as a pressuresensitive adhesive layer.

The pressure sensitive adhesive optical film is cut into a size of adisplay in use. Contact of an end (cut end) of the pressure sensitiveadhesive optical film to a people and an equipment may cause omission ofthe pressure sensitive adhesive in a contact portion in case of handlingin the process for the use. Since attachment on a liquid crystal cell ofa pressure sensitive adhesive optical film with omission of a pressuresensitive adhesive disables adhesion of the omitted portion, the portionreflects light, and as a result there may occur a problem of a displaydefect. Recently an edge of a display is required especially to benarrower and then a defect generated at the end markedly reduces displayquality.

The present invention aims at providing a pressure sensitive adhesiveoptical film in which a pressure sensitive adhesive layer(s) islaminated on at least one surface of the optical film, wherein thepressure sensitive adhesive optical film does not cause omission of thepressure sensitive adhesive by contact of an end thereof in case ofhandling in the process for the use, and provides easy handling.

Furthermore, it aims at providing an image viewing display using thepressure sensitive adhesive optical film concerned.

DESCRIPTION OF THE INVENTION

As a result of wholehearted research made by the present inventors inorder to solve the above-mentioned problems, it was found out that theobject might be attained using a following pressure sensitive adhesiveoptical film, thus leading to completion of the present invention.

That is, the invention relates to a pressure sensitive adhesive opticalfilm with a pressure sensitive adhesive layer laminated on at least onesurface of an optical film, wherein the pressure sensitive adhesivelayer is laminated through an anchor layer formed of resin emulsions.

In a pressure sensitive adhesive optical film of the invention, based ona consideration that omission of pressure sensitive adhesives originatesmainly in a low adhesive properties between a pressure sensitiveadhesive layer and an optical film base material, it has become possiblethat intervention of an anchor layer formed of resin emulsions betweenthe pressure sensitive adhesive layer and the optical film base materialimproves adhesive properties between the pressure sensitive adhesivelayer and the optical film. This can greatly reduce partial omission ofthe pressure sensitive adhesives at a film end in case of handling ofthe pressure sensitive adhesive optical film, and also can improvehandling property of the pressure sensitive adhesive optical film.Moreover, resin emulsions can form a pressure sensitive adhesive layer,without changing in quality of the optical film concerned, whenmaterials of the optical film have inferior solvent resistance. Forexample, in the pressure sensitive adhesive optical film, also whenmaterials of the optical film surface on which an anchor layer islaminated are of polycarbonate and norbornene based resins, change inquality of material may be suppressed.

In the pressure sensitive adhesive optical film, the anchor layerpreferably has a thickness not less than twice of mean particle diameterof the resin emulsions. Moreover, a thickness of the anchor layer is setso as to give a value of not less than twice a mean particle diameter ofthe resin emulsion used for formation material of the anchor layer,which can give a sufficient strength for the anchor layer, and therebycan improve adhesive properties. A thickness of the anchor layer of lessthan twice of the mean particle diameter of the resin emulsions cannotgive a sufficient strength, resulting in inadequate adhesive properties.A thickness of the anchor layer is preferably not less than 4 times of amean particle diameter of the resin emulsions, and more preferably notless than 6 times. In addition, since an excessive thickness of theanchor layer may have adverse influence on adhesive physical properties,it is usually preferably not more than 500 times of a mean particlediameter of the resin emulsions.

In the pressure sensitive adhesive optical film, it is preferable that athickness of the anchor layer is not less than 100 nm. When a thicknessof the anchor layer becomes thinner, it may no longer have a characteras bulk material, but fails to show a sufficient strength, and as aresult sometimes sufficient adhesive properties may not be obtained. Athickness of the anchor layer is preferably not less than 100 nm, morepreferably not less than 200 nm, and still more preferably not less than250 nm. In addition, a thickness of the anchor layer is usuallypreferably not more than 3 μm in view of optical characteristics.

Preferable embodiment is that in the pressure sensitive adhesive opticalfilm, resin emulsions are of ethyleneimine addition products and/orpolyethylene imine addition products of acrylic based polymer emulsions,and a base polymer of a pressure sensitive adhesive for forming apressure sensitive adhesive layer includes functional groups reactivewith amino groups.

Acrylic based polymer emulsions used for formation materials of ananchor layer comprise resin beads synthesized by emulsionpolymerization, and by converting the beads to ethyleneimine additionproducts and/or polyethylene imine addition products, primary aminogroups may be effectively unevenly distributed in a resin beads surfaceportion. On the other hand, in the pressure sensitive adhesive forforming the pressure sensitive adhesive layer, a pressure sensitiveadhesive including functional groups reactive with amino groups is usedas a base polymer, and thereby in a surface boundary and vicinitybetween the anchor layer and the pressure sensitive adhesive layer,amino groups of in the anchor layer and functional groups in thepressure sensitive adhesive layer may react with each other to enableformation of a firm adhesive properties between the anchor layer and thepressure sensitive adhesive layer. And since the resin beads aresynthesized by emulsion polymerization and have high rate ofpolymerization and high force of coagulation of the resin, as a result,they exhibit outstanding mechanical strength, which is effective inpreventing pressure sensitive adhesive omission also from this pointview.

In addition, an example is known that an anchor layer of anethyleneimine addition product of a polyacrylic ester is prepared as ananchor layer between a pressure sensitive adhesive layer and an opticalfilm base material (Japanese Patent Laid-Open No. 10-20118 officialreport). However, the resin that forms the anchor layer is a solventtype resin, in the above-mentioned example, and even if ethyleneimine isadded to the resin, only primary amine may be introduced into the resin,which does not provide a structure enabling uneven distribution of theprimary amine on a bead surface thereof as in the invention. Moreover,the polyacrylic ester portion does not work effectively for adhesiveproperties with the base material. Therefore, it may not be understoodthat the anchor layer given in the official report can fully improve theadhesive properties between the pressure sensitive adhesive layer andthe optical film base material. Furthermore, since the ethyleneimineaddition product of the polyacrylic ester requires coating in a state ofbeing diluted with organic solvents, the organic solvent will adverselyaffect the materials, when the optical film materials are ofpolycarbonate and norbornene based resins.

A preferable embodiment of the invention is that functional groupsreactive with amino groups included in a base polymer of a pressuresensitive adhesive for forming the pressure sensitive adhesive layer areof a carboxyl group. Carboxyl groups have excellent reactivity withamino groups and are suitable as the functional groups included in thebase polymer, and moreover provide excellent adhesive properties betweenthe pressure sensitive adhesive layer and the anchor layer.

A preferable embodiment of the invention is that the acrylic basedpolymer emulsions are of acrylic/styrene copolymer emulsions. Copolymeremulsions of styrene based monomers as monomers constituting the acrylicbased polymer emulsions enables further improvement in mechanicalstrength.

Moreover, a preferable embodiment of the invention is that theabove-mentioned resin emulsions are emulsions of polyurethane resins inthe pressure sensitive adhesive optical film. Moreover, glass transitiontemperature (Tg) of the polyurethane resins is preferably not more than−30° C. Polyurethane resins advantageously have high flexibility inmolecular designing, and moreover, the resins having glass transitiontemperature of not more than −30° C. have excellent diffusibility in thepressure sensitive adhesive layer, which may exhibit excellentautohesion effect between emulsion particles.

Moreover, in the pressure sensitive adhesive optical film, an opticalfilm preferably has activation treatment performed thereto. Activationtreatment given to the optical film can suppress crawling at the time offormation of the anchor layer onto the optical film, which enables easyformation of the anchor layer with excellent adhesive properties on theoptical film.

Moreover, the invention relates to an image viewing display using the atleast one pressure sensitive adhesive optical films. According tovarious kinds of utilization embodiments of the image viewing displays,such as liquid crystal displays, the pressure sensitive adhesive opticalfilms of the invention may be used independently or two or more of themmay be used in combination.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view of a pressure sensitive adhesiveoptical film of the present invention; and

FIG. 2 is a cross-sectional enlarged view of a pressure sensitiveadhesive optical film of the invention.

BEST MODE FOR CARRYING-OUT OF THE INVENTION

As pressure sensitive adhesives for forming a pressure sensitiveadhesive layer of a pressure sensitive adhesive optical film of thepresent invention, various kinds of pressure sensitive adhesives, suchas rubber based pressure sensitive adhesives, acrylic based pressuresensitive adhesives, and silicone based pressure sensitive adhesives,may be used. In general, acrylic based pressure sensitive adhesiveshaving colorless transparency and excellent adhesive property withliquid crystal cells etc. are used.

Acrylic based pressure sensitive adhesives have, as a base polymer,acrylic polymers having a monomer unit of alkyl (meth)acrylate as aprincipal skeleton. In addition, (meth)acrylate represents acrylateand/or methacrylate and (meth) used in the invention has a same meaning.An average carbon number of alkyl groups of alkyl (meth)acrylates thatconstitute a principal skeleton of the acrylic polymer is about 1 to 12,and as examples of alkyl (meth)acrylates, there may be mentioned: methyl(meth)acrylates, ethyl (meth)acrylates, butyl (meth)acrylates, 2-ethylhexyl (meth)acrylates, etc. These may be used independently, or may beused in combination. Among them, alkyl (meth)acrylates of alkyl groupsof carbon numbers of 1 to 7 are preferable.

Various functional groups may be introduced into the base polymer suchas acrylic polymers. When resin emulsions having amino groups, such asethyleneimine addition products and/or polyethylene imine additionproducts of acrylic based polymer emulsions, are used as resin emulsionsof the anchor layer, functional groups reactive with amino groups areused as the functional groups. As functional groups reactive with aminogroups, for example, carboxyl group, epoxy group, isocyanate group, etc.may be mentioned. Moreover, a preferable embodiment is that when usingresin emulsions having isocyanate group at end groups, such aspolyurethane resins, as a resin emulsion, a base polymer of the pressuresensitive adhesive that forms a pressure sensitive adhesive layerincludes functional groups reactive with isocyanate group, such as aminogroup, carboxyl group, and hydroxyl group. Carboxyl group is suitableamong these functional groups. Acrylic polymers having the functionalgroups include monomer units having the functional groups concerned.

As monomers having carboxyl group, acrylic acid, methacrylic acid,fumaric acid, maleic acid, itaconic acid, etc. may be mentioned.Glycidyl (meth)acrylates etc. may be mentioned as monomers includingepoxy groups. As monomers having hydroxyl group, monomers includinghydroxyl group, such as 2-hydroxy ethyl (meth)acrylate and N-methylol(meth)acrylamide; hydroxy butyl (meth)acrylate; hydroxy hexyl(meth)acrylate etc. may be mentioned. Furthermore, as monomers includingN element, there may be mentioned: (meth)acrylamide, N,N-dimethyl(meth)acrylamide, N,N-diethyl (meth)acrylamide, (meth)acryloylmorpholine, (meth)acetonitrile , vinyl pyrrolidone, N-cyclohexylmaleimide, itaconimide, N,N-dimethylamino ethyl (meth)acrylamide etc. Inaddition, vinyl acetate, styrene, etc. may further be used for theacrylic polymers in a range that does not impair performance of thepressure sensitive adhesives. These monomers may be used independentlyor two or more kinds of them may be used in combination.

Although a ratio of a monomer unit having the functional groups in theacrylic polymer is not especially limited, a weight ratio (a/A) with amonomer unit (A) (wherein except for the above-mentioned monomer unit(a)) constituting the acrylic polymers is about 0.001 to 0.12, andpreferably 0.005 to 0.1.

Although an average molecular weight of the acrylic polymer is notespecially limited, a weight average molecular weight (by GPC) ispreferably about 300,000 to 2,500,000. The acrylic polymer may bemanufactured using suitably selected various well-known methods, forexample, radical-polymerization methods, such as a bulk polymerizationmethod, a solution-polymerization method, and asuspension-polymerization method. As radical polymerization initiators,various kinds of well-known azo based and peroxide based polymerizationinitiators may be used. A reaction temperature is usually about 50 to85° C., and reaction time is about 1 to 8 hours. Moreover, also amongthe manufacturing methods, a solution-polymerization method ispreferable, and polar solvents, such as ethyl acetate and toluene, aregenerally used as solvents for acrylic polymers. A solutionconcentration is usually about 20 to 80% by weight.

As base polymers of rubber based pressure sensitive adhesives, forexample, there may be mentioned: natural rubbers, isoprene rubbers,styrene butadiene based rubbers, reclaimed rubbers, polyisobutylenebased rubbers, and furthermore styrene-isoprene-styrene based rubbers,styrene-butadiene-styrene based rubbers, etc., and as base polymers ofsilicone based pressure sensitive adhesives, for example, dimethylpolysiloxanes, diphenyl polysiloxanes, etc. may be mentioned, andpolymers into which functional groups reactive with amino groups, suchas carboxyl groups are introduced may suitably be used.

Moreover, the pressure sensitive adhesive is preferably a pressuresensitive adhesive composition including crosslinking agents. Aspolyfunctional compounds that may be blended with the pressure sensitiveadhesive, organic crosslinking agents and polyfunctional metal chelatesmay be mentioned. As organic based crosslinking agents, epoxy basedcrosslinking agents, isocyanate based crosslinking agents, imine basedcrosslinking agents, etc. may be mentioned. As organic basedcrosslinking agents, isocyanate based crosslinking agents arepreferable. Polyfunctional metal chelates are substances havingpolyvalent metals that have a coordinate bond or a covalent bond withorganic compounds. As polyvalent metal atoms, Al, Cr, Zr, Co, Cu, Fe,Ni, V, Zn, In, Ca, Mg, Mn, Y, Ce, Sr, Ba, Mo, La, Sn, Ti, etc. may bementioned. An oxygen atom etc. may be mentioned as an atom in organiccompounds constituting a covalent bond or a coordinate bond, and asorganic compounds, alkyl esters, alcohol compounds, carboxylic acidcompounds, ether compounds, ketone compounds, etc. may be mentioned.

Although a blending ratio of a base polymer, such as acrylic polymers,and a crosslinking agent is not especially limited, but usually,preferably the crosslinking agent (solid content) is about 0.01 to 6parts by weight to the base polymer (solid content) 100 parts by weight,and more preferably 0.1 to 3 parts by weight.

Furthermore, to the pressure sensitive adhesive, if necessary, there maysuitably be used tackifiers, plasticizers, glass fibers, glass beads,fillers comprising metal powders, other inorganic powders, etc.,pigments, colorants, fillers, antioxidants, ultraviolet absorbers,silane coupling agents etc. Moreover, various kinds of additives in arange that does not depart from purposes of the invention may also besuitably used. A pressure sensitive adhesive layer showing lightdiffusibility obtained by adding micro-particles is also employable.

The anchor layer is formed of resin emulsions. As resin emulsions,various kinds of resin emulsions may be used, for example, resinemulsions obtained by emulsion polymerization of acrylic based monomersetc., and furthermore, resin emulsions to which various kinds ofdenaturation is given to the obtained emulsion polymerized polymers etc.Moreover, as resin emulsions there may be used resin emulsions obtainedby emulsifying various kinds of resins, such as polyurethanes andpolyesters using emulsifiers, and resin emulsions obtained as aself-emulsified emulsion by introducing water dispersible anion groups,cationic groups, or nonion groups into the above-mentioned resins.

Although a mean particle diameter of the resin emulsions is notespecially limited, it is preferably about 5 to 500 nm, and morepreferably 10 to 300 nm.

As resin emulsions used for formation of an anchor layer of theinvention, for example, ethyleneimine addition products and/orpolyethylene imine addition products of acrylic based polymer emulsionsmay be suitably used. The acrylic based polymer emulsion may beobtained, according to conventional methods, by carrying out emulsionpolymerization of alkyl (meth)acrylates and copolymerizable monomersthereof constituting base polymers (acrylic polymers) of the acrylicbased pressure sensitive adhesives mentioned above. As copolymerizablemonomers, in order to make ethyleneimine etc. react, monomers havingfunctional groups such as carboxyl group etc. may be used. A percentageto be used of monomers having functional groups, such as carboxyl group,is suitably adjusted based on a percentage of such as ethyleneimine tobe reacted. Moreover, as copolymerizable monomers, styrene basedmonomers are preferably used, as mentioned above.

Ethyleneimine and/or polyethylene imines are made to react to theacrylic based polymer emulsions to obtain addition products. By reactingethyleneimine to carboxyl group in the acrylic based polymer emulsionsetc., resins with an amino ethyl group as a primary amine group beinggrafted at a terminal group may be obtained. Polyethylene imine additionproducts may be obtained from the ethyleneimine by additionpolymerization. Moreover, addition products with polyethylene iminegrafted thereto may also be obtained by reacting separately synthesizedpolyethylene imine to carboxyl groups in acrylic based polymer emulsionsetc. In the ethyleneimine addition products and/or polyethylene imineaddition products of the acrylic based polymer emulsions, amine hydrogenequivalent is preferably about 300 to 800 g-solid/eq.

Ethyleneimine addition products and/or polyethylene imine additionproducts of the acrylic based polymer emulsions are not especiallylimited, but various kinds may be used. For example, as examples ofcommercially available article, POLYMENT SK-1000 by NIPPON SHOKUBAI Co.,Ltd. may be mentioned.

Moreover, as resin emulsions used for formation of the anchor layer,resin emulsions of polyurethanes may suitably be used. Adeka BontighterHUX series by Asahi Denka Co., Ltd. that is self-emulsified withoutemulsifiers may be mentioned as resin emulsions of polyurethanes.

Moreover, compounds reactive with resin emulsions may be mixed inaddition to the resin emulsions in formation of the anchor layer to forma cross-linking, enabling improvement in strength of the anchor layer.Epoxy compounds etc. may be illustrated as compounds reactive with theresin emulsions.

In a pressure sensitive adhesive optical film of the invention, as shownin FIG. 1, a pressure sensitive adhesive layer 3 is formed onto anoptical film 1 through the anchor layer 2. Moreover, a releasing sheet 4may be formed on the pressure sensitive adhesive layer 3.

Films used for formation of a liquid crystal display etc. are used asthe optical film 1, and types of the films are not especially limited.As optical films, for example, a polarizing film(polarizing plate),films of types having a transparent protective film are used on one sideor both sides of a polarizer.

A polarizer is not limited especially but various kinds of polarizer maybe used. As a polarizer, for example, a film that is uniaxiallystretched after having dichromatic substances, such as iodine anddichromatic dye, absorbed to hydrophilic high molecular weight polymerfilms, such as polyvinyl alcohol type film, partially formalizedpolyvinyl alcohol type film, and ethylene-vinyl acetate copolymer typepartially saponified film; poly-ene type alignment films, such asdehydrated polyvinyl alcohol and dehydrochlorinated polyvinyl chloride,etc. may be mentioned. In these, a polyvinyl alcohol type film on whichdichromatic materials (iodine, dyes) is absorbed and aligned afterstretched is suitably used. Although thickness of polarizer is notespecially limited, the thickness of about 5 to 80 μm is commonlyadopted.

A polarizer that is uniaxially stretched after a polyvinyl alcohol typefilm dyed with iodine is obtained by stretching a polyvinyl alcohol filmby 3 to 7 times the original length, after dipped and dyed in aqueoussolution of iodine. If needed the film may also be dipped in aqueoussolutions, such as boric acid and potassium iodide, which may includezinc sulfate, zinc chloride. Furthermore, before dyeing, the polyvinylalcohol type film may be dipped in water and rinsed if needed. Byrinsing polyvinyl alcohol type film with water, effect of preventingun-uniformity, such as unevenness of dyeing, is expected by makingpolyvinyl alcohol type film swelled in addition that also soils andblocking inhibitors on the polyvinyl alcohol type film surface may bewashed off. Stretching may be applied after dyed with iodine or may beapplied concurrently, or conversely dyeing with iodine may be appliedafter stretching. Stretching is applicable in aqueous solutions, such asboric acid and potassium iodide, and in water bath.

As a materials forming the protective film prepared in one side or bothsides of the above-mentioned polarizer, with outstanding transparency,mechanical strength, heat stability, moisture cover property, isotropy,etc. may be preferable. As materials of the above-mentioned protectivefilm, for example, polyester type polymers, such as polyethyleneterephthalate and polyethylenenaphthalate; cellulose type polymers, suchas diacetyl cellulose and triacetyl cellulose; acrylics type polymer,such as poly methylmethacrylate; styrene type polymers, such aspolystyrene and acrylonitrile-styrene copolymer (AS resin);polycarbonate type polymer may be mentioned. Besides, as examples of thepolymer forming a protective film, polyolefin type polymers, such aspolyethylene, polypropylene, polyolefin that has cyclo-type ornorbornene structure, ethylene-propylene copolymer; vinyl chloride typepolymer; amide type polymers, such as nylon and aromatic polyamide;imide type polymers; sulfone type polymers; polyether sulfone typepolymers; polyether-ether ketone type polymers; poly phenylene sulfidetype polymers; vinyl alcohol type polymer; vinylidene chloride typepolymers; vinyl butyral type polymers; allylate type polymers;polyoxymethylene type polymers; epoxy type polymers; or blend polymersof the above-mentioned polymers may be mentioned. Films made of heatcuring type or ultraviolet ray curing type resins, such as acryl based,urethane based, acryl urethane based, epoxy based, and silicone based,etc. may be mentioned.

In general, a thickness of a transparent protective film is 500 μm ormore, preferably 1 through 300 μm, and especially preferably 5 through200 μm.

As a transparent protective film, if polarization property anddurability are taken into consideration, cellulose based polymer, suchas triacetyl cellulose, is preferable, and especially triacetylcellulose film is suitable. In addition, when transparent protectivefilms are provided on both sides of the polarizer, transparentprotective films comprising same polymer material may be used on both ofa front side and a back side, and transparent protective filmscomprising different polymer materials etc. may be used.

Moreover, as is described in Japanese Patent Laid-Open Publication No.2001-343529 (WO 01/37007), polymer films, for example, resincompositions including (A) thermoplastic resins having substitutedand/or non-substituted imido group is in side chain, and (B)thermoplastic resins having substituted and/or non-substituted phenyland nitrile group in sidechain may be mentioned. As an illustrativeexample, a film may be mentioned that is made of a resin compositionincluding alternating copolymer comprising iso-butylene and N-methylmaleimide, and acrylonitrile-styrene copolymer. A film comprisingmixture extruded article of resin compositions etc. may be used.

Moreover, it is preferable that the transparent protective film may haveas little coloring as possible. Accordingly, a protective film having aphase difference value in a film thickness direction represented byRth=[(nx+ny)/2−nz]×d of −90 nm through +75 nm (where, nx and nyrepresent principal indices of refraction in a film plane, nz representsrefractive index in a film thickness direction, and d represents a filmthickness) may be preferably used. Thus, coloring (optical coloring) ofpolarizing plate resulting from a protective film may mostly becancelled using a protection film having a phase difference value (Rth)of −90 nm through +75 nm in a thickness direction. The phase differencevalue (Rth) in a thickness direction is preferably −80 nm through +60nm, and especially preferably −70 nm through +45 nm.

As a protective film, if polarization property and durability are takeninto consideration, cellulose based polymer, such as triacetylcellulose, is preferable, and especially triacetyl cellulose film issuitable. In addition, when the protective films are provided on bothsides of the polarizer, the protective films comprising same polymermaterial may be used on both of a front side and a back side, and theprotective films comprising different polymer materials etc. may beused. Adhesives are used for adhesion processing of the above describedpolarizer and the protective film. As adhesives, isocyanate derivedadhesives, polyvinyl alcohol derived adhesives, gelatin derivedadhesives, vinyl polymers derived latex type, aqueous polyurethane basedadhesives, aqueous polyesters derived adhesives, etc. may be mentioned.

A hard coat layer may be prepared, or antireflection processing,processing aiming at sticking prevention, diffusion or anti glare may beperformed onto the face on which the polarizing film of the abovedescribed protective film has not been adhered.

A hard coat processing is applied for the purpose of protecting thesurface of the polarization plate from damage, and this hard coat filmmay be formed by a method in which, for example, a curable coated filmwith excellent hardness, slide property etc. is added on the surface ofthe protective film using suitable ultraviolet curable type resins, suchas acrylic type and silicone type resins. Antireflection processing isapplied for the purpose of antireflection of outdoor daylight on thesurface of a polarization plate and it may be prepared by forming anantireflection film according to the conventional method etc. Besides, asticking prevention processing is applied for the purpose of adherenceprevention with adjoining layer.

In addition, an anti glare processing is applied in order to prevent adisadvantage that outdoor daylight reflects on the surface of apolarization plate to disturb visual recognition of transmitting lightthrough the polarization plate, and the processing may be applied, forexample, by giving a fine concavo-convex structure to a surface of theprotective film using, for example, a suitable method, such as roughsurfacing treatment method by sandblasting or embossing and a method ofcombining transparent fine particle. As a fine particle combined inorder to form a fine concavo-convex structure on the above-mentionedsurface, transparent fine particles whose average particle size is 0.5to 50 μm, for example, such as inorganic type fine particles that mayhave conductivity comprising silica, alumina, titania, zirconia, tinoxides, indium oxides, cadmium oxides, antimony oxides, etc., andorganic type fine particles comprising cross-linked of non-cross-linkedpolymers may be used. When forming fine concavo-convex structure on thesurface, the amount of fine particle used is usually about 2 to 50weight part to the transparent resin 100 weight part that forms the fineconcavo-convex structure on the surface, and preferably 5 to 25 weightpart. An anti glare layer may serve as a diffusion layer (viewing angleexpanding function etc.) for diffusing transmitting light through thepolarization plate and expanding a viewing angle etc.

In addition, the above-mentioned antireflection layer, stickingprevention layer, diffusion layer, anti glare layer, etc. may be builtin the protective film itself, and also they may be prepared as anoptical layer different from the protective film.

An optical film of the invention may be used in practical use as apolarizing plate laminated with other optical layers. Although there isespecially no limitation about the optical layers, one layer or twolayers or more of optical layers, which may be used for formation of aliquid crystal display etc., such as a reflective plate, a transflectiveplate, a retardation plate (a half wavelength plate and a quarterwavelength plate included), and a viewing angle compensation film, maybe used. Especially preferable polarizing plates are; a reflection typepolarization plate or a transflective type polarization plate in which areflective plate or a transfilective reflective plate is furtherlaminated onto a polarizing plate of the present invention; anelliptically polarizing plate or a circular polarizing plate in which aretardation plate is further laminated onto the polarizing plate; a wideviewing angle polarization plate in which a viewing angle compensationfilm is further laminated onto the polarizing plate; or a polarizingplate in which a brightness enhancement film is further laminated ontothe polarizing plate.

A reflective layer is prepared on a polarization plate to give areflection type polarization plate, and this type of plate is used for aliquid crystal display in which an incident light from a view side(display side) is reflected to give a display. This type of plate doesnot require built-in light sources, such as a backlight, but has anadvantage that a liquid crystal display may easily be made thinner. Areflection type polarization plate may be formed using suitable methods,such as a method in which a reflective layer of metal etc. is, ifrequired, attached to one side of a polarization plate through atransparent protective layer etc.

As an example of a reflection type polarization plate, a plate may bementioned on which, if required, a reflective layer is formed using amethod of attaching a foil and vapor deposition film of reflectivemetals, such as aluminum, to one side of a matte treated protectivefilm. Moreover, a different type of plate with a fine concavo-convexstructure on the surface obtained by mixing fine particle into theabove-mentioned protective film, on which a reflective layer ofconcavo-convex structure is prepared, may be mentioned. The reflectivelayer that has the above-mentioned fine concavo-convex structurediffuses incident light by random reflection to prevent directivity andglaring appearance, and has an advantage of controlling unevenness oflight and darkness etc. Moreover, the protective film containing thefine particle has an advantage that unevenness of light and darkness maybe controlled more effectively, as a result that an incident light andits reflected light that is transmitted through the film are diffused. Areflective layer with fine concavo-convex structure on the surfaceeffected by a surface fine concavo-convex structure of a protective filmmay be formed by a method of attaching a metal to the surface of atransparent protective layer directly using, for example, suitablemethods of a vacuum evaporation method, such as a vacuum depositionmethod, an ion plating method, and a sputtering method, and a platingmethod etc.

Instead of a method in which a reflection plate is directly given to theprotective film of the above-mentioned polarization plate, a reflectionplate may also be used as a reflective sheet constituted by preparing areflective layer on the suitable film for the transparent film. Inaddition, since a reflective layer is usually made of metal, it isdesirable that the reflective side is covered with a protective film ora polarization plate etc. when used, from a viewpoint of preventingdeterioration in reflectance by oxidation, of maintaining an initialreflectance for a long period of time and of avoiding preparation of aprotective layer separately etc.

In addition, a transflective type polarizing plate may be obtained bypreparing the above-mentioned reflective layer as a transflective typereflective layer, such as a half-mirror etc. that reflects and transmitslight. A transfiective type polarization plate is usually prepared inthe backside of a liquid crystal cell and it may form a liquid crystaldisplay unit of a type in which a picture is displayed by an incidentlight reflected from a view side (display side) when used in acomparatively well-lighted atmosphere. And this unit displays a picture,in a comparatively dark atmosphere, using embedded type light sources,such as a back light built in backside of a transflective typepolarization plate. That is, the transfilective type polarization plateis useful to obtain of a liquid crystal display of the type that savesenergy of light sources, such as a back light, in a well-lightedatmosphere, and can be used with a built-in light source if needed in acomparatively dark atmosphere etc.

The above-mentioned polarization plate may be used as ellipticallypolarization plate or circularly polarization plate on which theretardation plate is laminated. A description of the above-mentionedelliptically polarization plate or circularly polarization plate will bemade in the following paragraph. These polarization plates changelinearly polarized light into elliptically polarized light or circularlypolarized light, elliptically polarized light or circularly polarizedlight into linearly polarized light or change the polarization directionof linearly polarization by a function of the retardation plate. As aretardation plate that changes circularly polarized light into linearlypolarized light or linearly polarized light into circularly polarizedlight, what is called a quarter wavelength plate (also called λ/4 plate)is used. Usually, half-wavelength plate (also called λ/2 plate) is used,when changing the polarization direction of linearly polarized light.

Elliptically polarization plate is effectively used to give a monochromedisplay without above-mentioned coloring by compensating (preventing)coloring (blue or yellow color) produced by birefringence of a liquidcrystal layer of a super twisted nematic (STN) type liquid crystaldisplay. Furthermore, a polarization plate in which three-dimensionalrefractive index is controlled may also preferably compensate (prevent)coloring produced when a screen of a liquid crystal display is viewedfrom an oblique direction. Circularly polarization plate is effectivelyused, for example, when adjusting a color tone of a picture of areflection type liquid crystal display that provides a colored picture,and it also has function of antireflection.

As retardation plates, birefringence films obtained by uniaxial orbiaxial stretching high polymer materials, oriented films of liquidcrystal polymers, and materials in which orientated layers of liquidcrystal polymers are supported with films may be mentioned. Although athickness of a retardation plate also is not especially limited, it isin general approximately 20 through 150 μm.

As high polymer materials, for example, polyvinyl alcohols, polyvinylbutyrals, polymethyl vinyl ethers, poly hydroxyethyl acrylates,hydroxyethyl celluloses, hydroxypropyl celluloses, methyl celluloses,polycarbonates, polyarylates, polysulfones, polyethylene terephthalates,polyethylene naphthalates, polyethersulfones, polyphenylene sulfides,polyphenylene oxides, polyallyl sulfones, polyvinyl alcohols,polyamides, polyimides, polyolefins, polyvinyl chlorides, cellulose typepolymers, or bipolymers, terpolymers, graft copolymers, blendedmaterials of the above-mentioned polymers may be mentioned. Thesepolymer raw materials make oriented materials (stretched film) using astretching process and the like.

As liquid crystalline polymers, for example, various kinds of polymersof principal chain type and side chain type in which conjugated linearatomic groups (mesogens) demonstrating liquid crystalline orientationare introduced into a principal chain and a side chain may be mentioned.As examples of principal chain type liquid crystalline polymers,polymers having a structure where mesogen groups are combined by spacerparts demonstrating flexibility, for example, polyester based liquidcrystalline polymers of nematic orientation property, discotic polymers,cholesteric polymers, etc. may be mentioned. As examples of side chaintype liquid crystalline polymers, polymers having polysiloxanes,polyacrylates, polymethacrylates, or polymalonates as a principal chainskeleton, and polymers having mesogen parts comprising para-substitutedring compound units providing nematic orientation property as sidechains via spacer parts comprising conjugated atomic groups may bementioned. These liquid crystalline polymers, for example, is obtainedby spreading a solution of a liquid crystal polymer on an orientationtreated surface where rubbing treatment was performed to a surface ofthin films, such as polyimide and polyvinyl alcohol, formed on a glassplate and or where silicon oxide was deposited by an oblique evaporationmethod, and then by heat-treating.

A retardation plate may be a retardation plate that has a properretardation according to the purposes of use, such as various kinds ofwavelength plates and plates aiming at compensation of coloring bybirefringence of a liquid crystal layer and of visual angle, etc., andmay be a retardation plate in which two or more sorts of retardationplates is laminated so that optical properties, such as retardation, maybe controlled.

The above-mentioned elliptically polarization plate and anabove-mentioned reflected type elliptically polarization plate arelaminated plate combining suitably a polarization plate or a reflectiontype polarization plate with a retardation plate. This type ofelliptically polarization plate etc. may be manufactured by combining apolarization plate (reflected type) and a retardation plate, and bylaminating them one by one separately in the manufacture process of aliquid crystal display. On the other hand, the polarization plate inwhich lamination was beforehand carried out and was obtained as anoptical film, such as an elliptically polarization plate, is excellentin a stable quality, a workability in lamination etc., and has anadvantage in improved manufacturing efficiency of a liquid crystaldisplay.

A viewing angle compensation film is a film for extending viewing angleso that a picture may look comparatively clearly, even when it is viewedfrom an oblique direction not from vertical direction to a screen. Assuch a viewing angle compensation retardation plate, in addition, a filmhaving birefringence property that is processed by uniaxial stretchingor orthogonal bidirectional stretching and a bidriectionally stretchedfilm as inclined orientation film etc. may be used. As inclinedorientation film, for example, a film obtained using a method in which aheat shrinking film is adhered to a polymer film, and then the combinedfilm is heated and stretched or shrinked under a condition of beinginfluenced by a shrinking force, or a film that is oriented in obliquedirection may be mentioned. The viewing angle compensation film issuitably combined for the purpose of prevention of coloring caused bychange of visible angle based on retardation by liquid crystal cell etc.and of expansion of viewing angle with good visibility.

Besides, a compensation plate in which an optical anisotropy layerconsisting of an alignment layer of liquid crystal polymer, especiallyconsisting of an inclined alignment layer of discotic liquid crystalpolymer is supported with triacetyl cellulose film may preferably beused from a viewpoint of attaining a wide viewing angle with goodvisability.

The polarization plate with which a polarization plate and a brightnessenhancement film are adhered together is usually used being prepared ina backside of a liquid crystal cell. A brightness enhancement film showsa characteristic that reflects linearly polarization light with apredetermined polarization axis, or circularly polarization light with apredetermined direction, and that transmits other light, when naturallight by back lights of a liquid crystal display or by reflection from aback-side etc., comes in. The polarization plate, which is obtained bylaminating a brightness enhancement film to a polarization plate, thusdoes not transmit light without the predetermined polarization state andreflects it, while obtaining transmitted light with the predeterminedpolarization state by accepting a light from light sources, such as abacklight. This polarization plate makes the light reflected by thebrightness enhancement film further reversed through the reflectivelayer prepared in the backside and forces the light re-enter into thebrightness enhancement film, and increases the quantity of thetransmitted light through the brightness enhancement film bytransmitting a part or all of the light as light with the predeterminedpolarization state. The polarization plate simultaneously suppliespolarized light that is difficult to be absorbed in a polarizer, andincreases the quantity of the light usable for a liquid crystal picturedisplay etc., and as a result luminosity may be improved. That is, inthe case where the light enters through a polarizer from backside of aliquid crystal cell by the back light etc. without using a brightnessenhancement film, most of the light, with a polarization directiondifferent from the polarization axis of a polarizer, is absorbed by thepolarizer, and does not transmit through the polarizer. This means thatalthough influenced with the characteristics of the polarizer used,about 50 percent of light is absorbed by the polarizer, the quantity ofthe light usable for a liquid crystal picture display etc. decreases somuch, and a resulting picture displayed becomes dark. A brightnessenhancement film does not enter the light with the polarizing directionabsorbed by the polarizer into the polarizer but reflects the light onceby the brightness enhancement film, and further makes the light reversedthrough the reflective layer etc. prepared in the backside to re-enterthe light into the brightness enhancement film. By this above-mentionedrepeated operation, only when the polarization direction of the lightreflected and reversed between the both becomes to have the polarizationdirection which may pass a polarizer, the brightness enhancement filmtransmits the light to supply it to the polarizer. As a result, thelight from a backlight may be efficiently used for the display of thepicture of a liquid crystal display to obtain a bright screen.

A diffusion plate may also be prepared between brightness enhancementfilm and the above described reflective layer, etc. A polarized lightreflected by the brightness enhancement film goes to the above describedreflective layer etc., and the diffusion plate installed diffusespassing light uniformly and changes the light state into depolarizationat the same time. That is, the diffusion plate returns polarized lightto natural light state. Steps are repeated where light, in theunpolarized state, i.e., natural light state, reflects throughreflective layer and the like, and again goes into brightnessenhancement film through diffusion plate toward reflective layer and thelike. Diffusion plate that returns polarized light to the natural lightstate is installed between brightness enhancement film and the abovedescribed reflective layer, and the like, in this way, and thus auniform and bright screen may be provided while maintaining brightnessof display screen, and simultaneously controlling non-uniformity ofbrightness of the display screen. By preparing such diffusion plate, itis considered that number of repetition times of reflection of a firstincident light increases with sufficient degree to provide uniform andbright display screen conjointly with diffusion function of thediffusion plate.

The suitable films are used as the above-mentioned brightnessenhancement film. Namely, multilayer thin film of a dielectricsubstance; a laminated film that has the characteristics of transmittinga linearly polarized light with a predetermined polarizing axis, and ofreflecting other light, an aligned film of cholesteric liquid-crystalpolymer; a film that has the characteristics of reflecting a circularlypolarized light with either left-handed or right-handed rotation andtransmitting other light, etc. may be mentioned.

Therefore, in the brightness enhancement film of a type that transmits alinearly polarized light having the above-mentioned predeterminedpolarization axis, by arranging the polarization axis of the transmittedlight and entering the light into a polarization plate as it is, theabsorption loss by the polarization plate is controlled and thepolarized light can be transmitted efficiently. On the other hand, inthe brightness enhancement film of a type that transmits a circularlypolarized light as a cholesteric liquid-crystal layer, the light may beentered into a polarizer as it is, but it is desirable to enter thelight into a polarizer after changing the circularly polarized light toa linearly polarized light through a retardation plate, taking controlan absorption loss into consideration. In addition, a circularlypolarized light is convertible into a linearly polarized light using aquarter wavelength plate as the retardation plate.

A retardation plate that works as a quarter wavelength plate in a widewavelength ranges, such as a visible-light region, is obtained by amethod in which a retardation layer working as a quarter wavelengthplate to a pale color light with a wavelength of 550 nm is laminatedwith a retardation layer having other retardation characteristics, suchas a retardation layer working as a half-wavelength plate. Therefore,the retardation plate located between a polarization plate and abrightness enhancement film may consist of one or more retardationlayers.

In addition, also in a cholesteric liquid-crystal layer, a layerreflecting a circularly polarized light in a wide wavelength ranges,such as a visible-light region, may be obtained by adopting aconfiguration structure in which two or more layers with differentreflective wavelength are laminated together. Thus a transmittedcircularly polarized light in a wide wavelength range may be obtainedusing this type of cholesteric liquid-crystal layer.

Moreover, the polarization plate may consist of multi-layered film oflaminated layers of a polarization plate and two of more of opticallayers as the above-mentioned separated type polarization plate.Therefore, a polarization plate may be a reflection type ellipticallypolarization plate or a semi-transmission type elliptically polarizationplate, etc. in which the above-mentioned reflection type polarizationplate or a transflective type polarization plate is combined with abovedescribed retardation plate respectively.

Although an optical film with the above described optical layerlaminated to the polarizing plate may be formed by a method in whichlaminating is separately carried out sequentially in manufacturingprocess of a liquid crystal display etc., an optical film in a form ofbeing laminated beforehand has an outstanding advantage that it hasexcellent stability in quality and assembly workability, etc., and thusmanufacturing processes ability of a liquid crystal display etc. may beraised. Proper adhesion means, such as an adhesive layer, may be usedfor laminating. On the occasion of adhesion of the above describedpolarizing plate and other optical films, the optical axis may be set asa suitable configuration angle according to the target retardationcharacteristics etc.

Formation methods of the anchor layer 2 to the above-mentioned opticalfilm 1 is not especially limited, and for example, a method of applyinga resin emulsion to an optical film 1, and then drying etc. may bementioned. In formation of the anchor layer 2, activation treatment maybe performed to the optical film 1. Various methods may be adopted asactivation treatment, and, for example, a corona treatment, alow-pressure UV treatment, a plasma treatment, etc. may be adopted.Activation treatment is effective especially in the case where theoptical film 1 is of polyolefine based resins or norbornene basedresins. When a contact angle between water and each film is controlledto be not more than 80°, and preferably not more than 75°, repelling maybe suppressed during coating of anchor agents. A thickness of the anchorlayer 2 (dried film thickness) is, as mentioned above, preferably notless than twice a mean particle diameter (a) of the resin emulsion. Inaddition, FIG. 2 is an enlarged view concerning the anchor layer 2 inFIG. 1, and shows a case where a thickness of the anchor layer 2 isabout 4 times the mean particle diameter (a) of the resin emulsion.Although a thickness of the anchor layer 2 is not especially limited,but it is preferably not less than 100 nm as described above.

The pressure sensitive adhesive layer 3 is formed by being laminated onthe anchor layer 2. Formation methods are not especially limited, butthere may be mentioned: a method of applying a pressure sensitiveadhesive (solution) on an anchor layer 2, and then drying; and a methodof transferring a layer using a releasing sheet 4 having a pressuresensitive adhesive layer 3 provided thereon etc. Although a thickness ofa pressure sensitive adhesive layer 3 (dried film thickness) is notespecially limited, it is preferably about 10 to 40 μm.

As a separator 4 material, papers, plastics films such as polyethylenepolypropylene, rubber sheets, cloths, no woven fabrics, nets, foamedsheets and metallic foils or laminated sheets thereof may be used. As asurface of the separator 4, if necessary, suitable conventional releaseagents, such as silicone type, long chain alkyl type, fluorine typerelease agents, is coated.

In addition, in the present invention, ultraviolet absorbing propertymay be given to the above-mentioned each layer, such as an optical filmetc. and an adhesive layer, using a method of adding UV absorbents, suchas salicylic acid ester type compounds, benzophenol type compounds,benzotriazol type compounds, cyano acrylate type compounds, and nickelcomplex salt type compounds.

Suitable liquid crystal displays, such as liquid crystal display withwhich the above-mentioned optical film has been located at one side orboth sides of the liquid crystal cell, and with which a backlight or areflective plate is used for a lighting system may be manufactured. Inthis case, the optical film by the present invention may be installed inone side or both sides of the liquid crystal cell. When installing theoptical films in both sides, they may be of the same type or ofdifferent type. Furthermore, in assembling a liquid crystal display,suitable parts, such as diffusion plate, anti-glare layer,antireflection film, protective plate, prism array, lens array sheet,optical diffusion plate, and backlight, may be installed in suitableposition in one layer or two or more layers.

Subsequently, organic electro luminescence equipment (organic ELdisplay) will be explained. Generally, in organic EL display, atransparent electrode, an organic luminescence layer and a metalelectrode are laminated on a transparent substrate in an orderconfiguring an emitting (organic electro luminescence emitting). Here, aorganic luminescence layer is a laminated material of various organicthin films, and much compositions with various combination are known,for example, a laminated material of hole injection layer comprisingtriphenylamine derivatives etc., a luminescence layer comprisingfluorescent organic solids, such as anthracene; a laminated material ofelectronic injection layer comprising such a luminescence layer andperylene derivatives, etc.; laminated material of these hole injectionlayers, luminescence layer, and electronic injection layer etc.

An organic EL display emits light based on a principle that positivehole and electron are injected into an organic luminescence layer byimpressing voltage between a transparent electrode and a metalelectrode, the energy produced by recombination of these positive holesand electrons excites fluorescent substance, and subsequently light isemitted when excited fluorescent substance returns to ground state. Amechanism called recombination which takes place in a intermediateprocess is the same as a mechanism in common diodes, and, as isexpected, there is a strong non-linear relationship between electriccurrent and luminescence strength accompanied by rectification nature toapplied voltage.

In an organic EL display, in order to take out luminescence in anorganic luminescence layer, at least one electrode must be transparent.The transparent electrode usually formed with transparent electricconductor, such as indium tin oxide (ITO), is used as an anode. On theother hand, in order to make electronic injection easier and to increaseluminescence efficiency, it is important that a substance with smallwork function is used for cathode, and metal electrodes, such as Mg—Agand Al—Li, are usually used.

In organic EL display of such a configuration, an organic luminescencelayer is formed by a very thin film about 10 nm in thickness. For thisreason, light is transmitted nearly completely through organicluminescence layer as through transparent electrode. Consequently, sincethe light that enters, when light is not emitted, as incident light froma surface of a transparent substrate and is transmitted through atransparent electrode and an organic luminescence layer and then isreflected by a metal electrode, appears in front surface side of thetransparent substrate again, a display side of the organic EL displaylooks like mirror if viewed from outside.

In an organic EL display containing an organic electro luminescenceemitting equipped with a transparent electrode on a surface side of anorganic luminescence layer that emits light by impression of voltage,and at the same time equipped with a metal electrode on a back side oforganic luminescence layer, a retardation plate may be installed betweenthese transparent electrodes and a polarization plate, while preparingthe polarization plate on the surface side of the transparent electrode.

Since the retardation plate and the polarization plate have functionpolarizing the light that has entered as incident light from outside andhas been reflected by the metal electrode, they have an effect of makingthe mirror surface of metal electrode not visible from outside by thepolarization action. If a retardation plate is configured with a quarterwavelength plate and the angle between the two polarization directionsof the polarization plate and the retardation plate is adjusted to π/4,the mirror surface of the metal electrode may be completely covered.

This means that only linearly polarized light component of the externallight that enters as incident light into this organic EL display istransmitted with the work of polarization plate. This linearly polarizedlight generally gives an elliptically polarized light by the retardationplate, and especially the retardation plate is a quarter wavelengthplate, and moreover when the angle between the two polarizationdirections of the polarization plate and the retardation plate isadjusted to π/4, it gives a circularly polarized light.

This circularly polarized light is transmitted through the transparentsubstrate, the transparent electrode and the organic thin film, and isreflected by the metal electrode, and then is transmitted through theorganic thin film, the transparent electrode and the transparentsubstrate again, and is turned into a linearly polarized light againwith the retardation plate. And since this linearly polarized light liesat right angles to the polarization direction of the polarization plate,it cannot be transmitted through the polarization plate. As the result,mirror surface of the metal electrode may be completely covered.

EXAMPLE

Although concrete description will be given hereinafter with referenceto Examples of the present invention, the present invention is notlimited to them. In addition, part represents part by weight in eachexample.

Example 1

(Production of an Optical Film)

After a polyvinyl alcohol film with a thickness of 80 μm was stretched 5times in 40° C. iodine aqueous solution, it was dried for 4 minutes at50° C. to obtain a polarizer. Triacetyl cellulose films were adhered onboth sides of this polarizer through a polyvinyl alcohol based adhesiveto obtain a polarizing plate.

(Formation of an anchor layer)

A solution diluted into 5% of a solid content was prepared by dissolvingAdeka Bontighter HUX 290H (an emulsion mean particle diameter of about42 nm) manufactured by Asahi Denka Co., Ltd., as a resin emulsion of apolyurethane, with a mixed solvent of water: butyl cellosolve=3: 1(volume ratio). This solution was applied on the polarizing plate usinga wire bar #5, and, subsequently volatile matter was evaporated off.Observation by a TEM ultrathin membrane section method of a thickness ofthe anchor layer after evaporated gave a thickness of 1000 nm, andshowed that 6 to 7 emulsion particles existed in a thickness direction.

(Formation of Pressure Sensitive Adhesive Layer)

As a base polymer, a solution (30% of solid content) including anacrylic polymer of a weight average molecular weight of 2,000,000consisting of a copolymer of butyl acrylate : acrylic acid: 2-hydroxyethyl acrylate =100:5:0.1 (weight ratio) was used. Into the acrylicpolymer solution were added Coronate L manufactured by NipponPolyurethane Co., Ltd. that is an isocyanate based polyfunctionalcompound 3.2 parts to 100 parts of a polymer solid content, an additive(manufactured by Shin-Etsu Chemical Co., Ltd., KBM 403) 0.6 parts, and asolvent for viscosity adjustment (ethyl acetate), to prepare a pressuresensitive adhesive solution (11% of solid content). The pressuresensitive adhesive solution concerned was applied on a releasing film(polyethylene terephthalate based material=Diafoil MRF 38, manufacturedby Mitsubishi Polyester Film Corporation) so that a thickness afterdried might gives 25 μm, and subsequently dried in a circulating hot airtype oven to form a pressure sensitive adhesive layer.

(Production of a Pressure Sensitive Adhesive Optical Film)

To an anchor layer formed on a surface of the polarizing plate, areleasing film having a pressure sensitive adhesive layer currentlyformed thereon was attached to produce a pressure sensitive adhesivepolarizing plate.

Example 2

(An Optical Film)

Corona treatment was given to a retardation plate (100 μm) using abiaxially stretched norbornene based resin (manufactured by JSR, Arton)(71° of an angle of contact with water), and the obtained plate wasused.

(Formation of an Anchor Layer)

As a polyethylene imine addition product of acrylic/styrene basedcopolymer emulsion, POLYMENT SK-1000 (an emulsion mean particle diameterof about 100 nm) manufactured by NIPPON SHOKUBAI Co., Ltd. was dissolvedwith a mixed solvent of water:isopropyl alcohol=1:3 (volume ratio), toprepare a solution diluted into 5% of a solid content. After thissolution was applied on the retardation plate using a wire bar #5,volatile matter was evaporated off. Observation by TEM ultrathinmembrane section method of a thickness of the anchor layer afterevaporated gave a thickness of 800 nm, and showed that 4 to 5 emulsionparticles existed in a thickness direction.

(Production of a Pressure Sensitive Adhesive Optical Film)

To the anchor layer formed on a surface of the retardation plate, areleasing film having a same pressure sensitive adhesive layer as inExample 1 currently formed thereon was attached to produce a pressuresensitive adhesive retardation plate.

Example 3

(Production of an Optical Film)

A solution obtained by dissolving flakes of a polycarbonate (PC) inmethylene chloride was uniformly cast a smooth SUS board, and theobtained board was dried in a solvent atmosphere so that the surfacemight not have dew formation. The obtained PC film was then removed fromthe SUS board after sufficient drying, and then dried in a circulatinghot air type oven to obtain a non-stretched film of PC (30μ). This filmwas stretched by 1.2 times while being heated, and corona treatment wasgiven to obtain a PC retardation plate (73° of an angle of contact withwater).

(Formation of an Anchor Layer)

An anchor layer was formed on the PC retardation plate as in Example 2.Observation by a TEM ultrathin membrane section method of a thickness ofthe anchor layer after evaporated gave a thickness of 800 nm, and showedthat 4 to 5 emulsion particles existed in a thickness direction.

(Production of a Pressure Sensitive Adhesive Optical Film)

To an anchor layer formed on a surface of the retardation plate, areleasing film having a same pressure sensitive adhesive layer as inExample 1 currently formed thereon was attached to produce a pressuresensitive adhesive retardation plate.

Referential Example 1

(An Optical Film)

A same polarizing plate as in Example 1 was used.

(Formation of an Anchor Layer)

As a resin emulsion of polyurethane, Adeka Bontighter HUX 290H (anemulsion mean particle diameter of about 42 nm) manufactured by AsahiDenka Co., Ltd. was dissolved with a mixed solvent of water: butylcellosolve=3: 1 (volume ratio) to prepare a solution diluted into 0.2%of solid content. This solution was applied on the polarizing plateusing a wire bar #5, and, subsequently volatile matter was evaporatedoff. Observation by a TEM ultrathin membrane section method of athickness of the anchor layer after evaporated gave a thickness of theanchor layer of 80 nm after evaporated, and showed that emulsionparticles was dotted and overlap of the emulsion particles could not beobserved in a thickness direction.

(Production of a Pressure Sensitive Adhesive Optical Film)

A releasing film having a same pressure sensitive adhesive layer as inExample 1 currently formed thereon was attached on the anchor layerformed on a surface of the polarizing plate to produce a pressuresensitive adhesive polarizing plate.

Referential Example 2

(An Optical Film)

A same polarizing plate as in Example 1 was used.

(Formation of a Pressure Sensitive Adhesive Layer)

As a base polymer, a solution (30% of solid content) including anacrylic polymer of a weight average molecular weight of 1,400,000consisting of a copolymer of butyl acrylate: 2-hydroxy ethylacrylate=100:0.5 (weight ratio) was used. Into the acrylic polymersolution were added Coronate L manufactured by Nippon Polyurethane Co.,Ltd. that is an isocyanate based polyfunctional compound 5 parts to 100parts of a polymer solid content, an additive (manufactured by Shin-EtsuChemical Co., Ltd., KBM 403) 0.5 parts, and a solvent for viscosityadjustment (toluene), to prepare a pressure sensitive adhesive solution(10% of a solid content). The pressure sensitive adhesive solutionconcerned was applied on a releasing film (polyethylene terephthalatebased material=Diafoil MRF 38, manufactured by Mitsubishi Polyester FilmCorporation) so that a thickness after dried may give 25 μm, andsubsequently dried in a circulating hot air type oven to form a pressuresensitive adhesive layer.

(Production of a Pressure Sensitive Adhesive Optical Film)

After forming an anchor layer on a surface of the polarizing plate as inExample 2, a releasing film having the pressure sensitive adhesive layerformed thereon was attached on the anchor layer to produce a pressuresensitive adhesive polarizing plate.

Comparative Example 1

Except for not having formed an anchor layer in Example 1, a same methodas in Example 1 was repeated to produce a pressure sensitive adhesivepolarizing plate.

Comparative Example 2

(An Optical Film)

A same polarizing plate as in Example 1 was used.

(Formation of an Anchor Layer)

A solution of POLYMENT NK 380 manufactured by NIPPON SHOKUBAI Co., Ltd.as a solvent type polyethylene imine based resin (ethyleneimine additionproduct of polyacrylic ester) was applied on the polarizing plate usinga wire bar #5, and subsequently volatile matter was evaporated off. Athickness of the anchor layer after evaporated gave 100 nm.

(Production of a Pressure Sensitive Adhesive Optical Film)

To an anchor layer currently formed on a surface of the polarizing platea releasing film having a same pressure sensitive adhesive layer as inExample 1 currently formed thereon was attached to produce a pressuresensitive adhesive polarizing plate.

Comparative Example 3

Except for not having formed an anchor layer in Example 3, a same methodas in Example 3 was repeated to produce a pressure sensitive adhesiveretardation plate.

The pressure sensitive adhesive optical films obtained in the Examplesand Comparative examples were evaluated for the following.

Table 1 shows the evaluation results.

(Pressure Sensitive Adhesive Omission)

A pressure sensitive adhesive optical film produced by the above methodwas die-cut by 25 mm×150 mm size with a Thomson blade die cut system. Acut end (25 mm width side) was contacted to a glass plate (manufacturedby Corning Inc., Corning 1737) 20 consecutive times. Then, the contactend of each pressure sensitive adhesive optical film was visuallychecked, and evaluated according to following criteria.

Moreover, an area of the pressure sensitive adhesive omission was alsoevaluated.

-   ◯: A pressure sensitive adhesive omission with a depth of not less    than 150 μm not observed-   Δ: A pressure sensitive adhesive omission with a depth of not less    than 300 μm not observed

×: A pressure sensitive adhesive omission with a depth of not less than300 μm observed TABLE 1 Anchor layer Existence of Magnification tocarboxyl a mean particle group of diameter of a pressure Pressuresensitive Thickness resin emulsion sensitive adhesive omission Opticalfilm Kind (nm) (times) adhesive layer Evaluation Area (mm²) Example 1Polarizing *1 1000 6 to 7 Included ◯ 0.1 plate Example 2 Retardation *2800 4 to 5 Included ◯ 0.3 plate Example 3 Retardation *2 800 4 to 5Included ◯ 0.2 plate Referential Polarizing *1 80 Not more than 1Included Δ 0.9 Example 1 plate Referential Polarizing *2 800 4 to 5 NotΔ 1.0 Example 2 plate included Comparative Polarizing Not used 0 0Included X 2.3 Example 1 plate Comparative Polarizing *3 100 — IncludedX 1.9 Example 2 plate Comparative Retardation Not used 0 0 Included X3.2 Example 3 plateIn Table 1:*1: Adeka Bontighter HUX 290H manufactured by Asahi Denka Co., Ltd.,*2: POLYMENT SK 1000 manufactured by NIPPON SHOKUBAI Co., Ltd.*3: POLYMENT NK 380 manufactured by NIPPON SHOKUBAI Co., Ltd.Industrial Applicability

The present invention is useful as polarizing plates, retardationplates, optical compensating films, brightness enhancement films, etc.,and furthermore is useful as a pressure sensitive adhesive optical filmapplied to optical films laminated thereto. The invention is alsosuitably applicable for image viewing displays, such as liquid crystaldisplays, organic EL viewing displays, and PDPs.

1. A pressure sensitive adhesive optical film having a pressuresensitive adhesive layer laminated on at least one surface of theoptical film, wherein the pressure sensitive adhesive layer is laminatedthrough an anchor layer formed of a resin emulsion, and a thickness ofthe anchor layer is not less than twice a mean particle diameter of theresin emulsion.
 2. (canceled).
 3. The pressure sensitive adhesiveoptical film according to claim 1, wherein a thickness of the anchorlayer is not less than 100 nm.
 4. The A pressure sensitive adhesiveoptical film having a pressure sensitive adhesive layer laminated on atleast one surface of the optical film, wherein the pressure sensitiveadhesive layer is laminated through an anchor layer formed of a resinemulsion, the resin emulsion is of an ethyleneimine addition productand/or a polyethylene imine addition product of an acrylic based polymeremulsion, and a base polymer of the pressure sensitive adhesive forforming the pressure sensitive adhesive layer includes a functionalgroup reactive with an amino group.
 5. The pressure sensitive adhesiveoptical film according to claim 4, wherein a functional group reactivewith an amino group included in the base polymer of the pressuresensitive adhesive for forming the pressure sensitive adhesive layer isof a carboxyl group.
 6. The pressure sensitive adhesive optical filmaccording to claim 5, wherein the acrylic based polymer emulsion is anacrylic/styrene based copolymer emulsion.
 7. The pressure sensitiveadhesive optical film according to claim 1, wherein the resin emulsionis an emulsion of a polyurethane resin.
 8. The pressure sensitiveadhesive optical film according to claim 7, wherein a glass transitiontemperature of the polyurethane resin is not more than −30° C.
 9. Thepressure sensitive adhesive optical film according to claim 1, whereinactivation treatment is given to the optical film.
 10. An image viewingdisplay using the at least one pressure sensitive adhesive optical filmaccording to claim
 1. 11. The pressure sensitive adhesive optical filmaccording to claim 4, wherein a thickness of the anchor layer is notless than twice a mean particle diameter of the resin emulsion.
 12. Thepressure sensitive adhesive optical film according to claim 4, wherein athickness of the anchor layer is not less than 100 nm.
 13. The pressuresensitive adhesive optical film according to claim 4, wherein activationtreatment is given to the optical film.
 14. An image viewing displayusing the at least one pressure sensitive adhesive optical filmaccording to claim 4.